Lithium-Lanthanide Bimetallic Metal-Organic Frameworks towards Negative Electrode Materials for Lithium-Ion Batteries

Novel lithium-lanthanide (Ln: cerium and praseodymium) bimetallic coordination polymers with formulas C₁₀ H₂ LnLiO₈ (Ln: Ce (CeLipma) and Pr (PrLipma)) and C₁₀ H₃ CeO₈ (Cepma) were prepared through a simple hydrothermal method. The three compounds were characterized by means of FTIR spectroscopy, X-ray diffraction, single-crystal X-ray diffraction, SEM, TEM, and X-ray photoelectron spectroscopy. The results of structural refinement show that they belong to triclinic symmetry and P $$ space group with cerium (or praseodymium) and lithium cations, forming coordination bonds to oxygen atoms from different pyromellitic acid molecules, and leading to the construction of 3D structures. It is interesting to note that the frameworks exclude any coordination water and lattice water. As an electrode material for lithium-ion batteries, CeLipma exhibits a maximum capacity of 800.5 mAh g^-1 and a retention of 91.4 % after 50 cycles at a current density of 100 mA g^-1 . The favorable electrochemical properties of the lanthanide coordination polymers show potential application prospects in the field of electrode materials.